First removed the little plastic cover at the base of the mirror, ( I used a really small flat blade screw driver) then there is a tab on the bottom inside of the mirror, press that then lift the mirror up. I just took my off when I tinted my windshield. PM me if you have any questions.

(on a 2007)
Look at the post that holds it to the window. Look at the backside (nearest window). There should be a little plastic cover piece that can be popped off.
After you pop this off, the mirror should slide off.

The windshield has a triangular metal piece in the window itself (so to speak). The rear view mirror has a similar sized and shape triangular piece that slides on the metal.

I need to move mine up also. I keep finding collisions off the port bow when I have it folded down. My eye height is aty mirror height and it's either foled up or down and dangerous. Did you figure out if it could be moved? Thanks.